Hydrogenizing olefinic terpene derivatives.



are a CARL PAAL, OF LEIPZIG, GERMANY.

HYDROGENIZING OLEFINIC TERPENE DERIVATIVES.

miihleniveg, Leipzi Kingdom of Saxony,v

German Empire, have invented a new and useful Improvement inHydrogenizing ()lefinic Terpene Derivatives; and I do hereby declare thefollowing to be a full, clear and exact description of the same.

The present process for hydrogenizing olefinic terpene derivatives hasthe purpose, to obtain from olefinic terpene derivatives containingoxygen-hydrogen, groups (for instance the alcohol-, aldehydeoracidgroup) the corresponding saturated compounds while maintaining theoxygen-hydrogen groups in unchanged state.

The process consists essentially in that the olefinic terpenederivatives in presence of so called adhesion compounds of the platinummetal group are subjected in neutral medium to the action of hydrogen.

I may use as adhesion compounds of the platinum metal group thecolloidal metals according to C. Paal (Bari/2km dc!" Deuts/rhen("hemisclzcn Gesell-s'cimft volume 37 page 124 (1904); "olume 38'page1398 (1905) German Patent 157172).

More suitable for carrying out the process are the adhesion compoundsobtained by precipitating platinum metals on pulverm lent. indifferentsubstances free of anticatalytic action. which platinum metals areretained by the pulverulent particles on behalf of the adhesion(adsorption) action, (see on such compounds Bem'chfe (.Zcr fhnzzsvrhm'iUhcmv'sclnm GeseZZscha-ft volume 4 page 1013 (1911); volume 46 page 30601913)). By the use of the said platinum metal compounds as catalysts inthe action of hydrogen one succeeds to hydrogenize olefinicterpenederivatives without forma-- tion of by-products, The olefinicterpene derivatives in question with one-double carbon linkage can betransformed, by transition into the single-linkage 'form, into thesaturated compounds, While those with two double carbon bonds can beconverted-by stages into the diand tetra-hydroderivatives, Without anychange taking place in the carbine], carboxylic or aldehyde group. Inthis way, according to the working conditions, geraniol can betransformed into citronellol (dihydrogeraniol) or tetrahydrogeraniol,linalool into dior tetra-hydroh- Specification of Letters Patent.

Patented Jan. 2, 1917.

Application filed July 18, 1914. Serial No. 851,794.

nalool, citral into citronellal (dihydrocitral) or tetrahyrlrocitral,geranic acid into citronellic acid (dihydrogeraniuni-acid) ortetrahydrogeranium acid; while the olefinic terpene derivativescontaining only one double linkage, as citronellol, eitronellal andcitronellic acid can he transformed into their saturateddihydro-compmmds.

The catalysts especially suitable for my process, containing as large asurface as possible, consisting of the platinum metals or theirprotohydroxi'ds, may be obtained by being deposited from the aqueoussolution of Plltilllllllilltitill salts on finely pulverulent substanceshaving with reference to their finely pulverulent state a large adheringsurface. Metals specially adapted to serve as catalyzer carriers are:magnesium, nickel and cobalt, treated, in the form of fine powder, witha solution of a palladiumor platinum salt, the palladium or platinumbeing precipitated as a thin metallic coating on the powdered metal.Other suitable mate" rials are the finely pulverulent oxids of the saidmetals, as precipitated magnesium hydroxid, magnesium or calciumcarbonate, \vhich react with solutions of salts of palladium or divalentplatinum, to form the protohydroxids, Pd(()l'l) and Pt(()H) the latterbeing deposited, as. a thin adherent stratum, on the powders; andfinally inert, finely powdered insoluble substances, such as bariumsulfate, kieselguhr, coal, Wood dust, sawdust, cellulose powder and thelike can also serve as catalyzer carriers, these being saturated withthe palladioor platinosalt solution and then treated with dilute soda.solution, thus precipitating the respective protohydroxids, as thincoatings, on the powders. The relative proportions between catalyzercarrier and catalyzer are preten ably chosen so that the former contain().5l% of palladium, as such or as protohydroxid, or 12% of platinum,also as metal or protohydroxid.

()ther suitablecatalysts for hydrogenizing oletinic terpene derivativeswith hydrogen are the colloidal adhesion platinum metals preparedaccording to the Paal process in using sodium protalbinate (Bem'chterlc'r' Dent-when Chemise/Len G'cscZZsc/mft volume 37, page 124 (1904);volume 38, page 1398 (1905)). The said compounds contain the metals onlyin a very finely divided state. The last named modification of myprocess by using the colloidal compounds according to Iaal is morecxpen' sive, than the use of the adhesion compounds on pulverulentsubstances, I because in the separation of the reaction products thecolloid inust be precipitated by acid, in which operation the colloid istransformed into the irreversible gel. The acid may also have atransforming action on the half hydrogenized olel'inic terpenederivatives. Because, however, the hydrogenizing process itself iscarried out in a neutral medium and the acid is added only afterthefinished reduction, one is able to reduce the transforming action ofthe acid to a minimum in avoiding the use of a surplus of acid. Forthese reasons it is even possible to obtain good technical results inusing the colloids according to laal,

The use of catalysts in which the. platinum metals have been imparted toas large surface as possible either by adhesion on .pulverulentsubstances or by transformation in the colloidal state according to thequoted method of laal presents furthermore the advantages that thecatalyst can be separated from the reduction product, simply and withoutloss, by filtration; and also that only very small quantities of theexpensive platinum metals are required.

One part of palladium or two parts of platinum will suffice-to reduce athousandfold quantity of an olefin terpene derivative. The process isalso capable of being carried out with still smaller quantities ofcataly-zer, though in such case it takes more time, the velocity of thereaction depending on the quantity'of the catalyst, and also. to asmaller extent, on the nature of the terpene derivatives, the doublyunsaturated forms of which are more easily and quickly reduced thanthose which have only one double carbon linkage. The reduction proceedsat ordinary temperature and atmospheric pressure, though a positivepressure of 2-4 atmospheres of hydrogen has an accelerative effect onthe process, without, however. being essential. The liquid olelinicterpene alcohols andaldehydes are also h v-.

drogenized without the application of any diluent, though it has beenfound advantageous to dilute them with a multiple volume of methylorethyl alcohol.

In using colloidal platinum metals according to laal aqueous solutionsof the same are mixed with the alcoholic solution of the terpenederivative to be hydrogenized. Substances with an anticatalytic ac-'tion, such as many metals and their compounds, for example lead, zinc.and the like; also carbon disulfid, chloroform, volatile compounds ofarsenic and phosphorus, sulfureted hydrogen and mineral acids; must beavoided, Thehydrogen used must also be free from anticatalytieconstituents.

One has already proposed to use platinum black in hydrogenizing terpenederivatives (Willstiitter, Bcrz'chte der [)cutschcn UhcmisckenGescllsclmftvolume 41, page 1475). In using platinum black one doeshowever not succeed in maintaining the oxygen hydrogen group inunchanged state, whereas hydrocarbons are formed in a high amount. -Forother hydrogenizing processes one has used palladium chlorid (AmericanPatent 1063746 Skita) or solid platinum salts (American Patent 1023753Paal). In this way however it is impossible to hydrogenize the olelinicterpene derivatives, because in the hydrogenizing process acid isliberated which has a decomposing or transforming action on oletinicterpene derivatives.

Ewamplcs.

l. lrof ressi've reduction of oitml, gemm'ol and lint/loot, t0 thecorreapomlin dihy drocump'oumls-JMr the semi-reduction, 1000 parts ofone of the above named, freshly distilled, doubly unsaturatedalcohols oraldehydes are mixed with a 7-8 fold-volume of 9 methylor ethyl alcohol(referred to the volume of the terpene derivative), whereupon '1 partorif the reduction is desired to be effected very quickly, 2 parts-ofpalladium or alternatively 2 or 4 parts of plati- 9 num, are added inthe form of one of the catalyzers mentioned above. Nevertheless, asalready stated, the reduction can also be carried on with smallerquantities of palladium or platinum, with a longer expenditure 1 oftime. a

Palladium protohydroxid or platinum protohydroxid deposited on finelypowdered calcium carbonate, has been found specially effective, usedeither direct or after careful 1 reduction with, hydrogen in the cold.The mixture is next placed in a closed vessel, taking care to preventcontact with any anticatalytic metals; and the amount of 1o hydrogenrequired for the semi-reduction is. intrmluced, at the ordinarytemperature and with constant process is stopped at once. The reductionis still more rapid when performed in an autoclave provided withstirring mechanism and 1 a pressure gage, the vessel being evacuated, toremove the air, when chargedwith t he catalyzer-aml the substance to bereduced, whereupon hydrogen is admitted under a positive pressiu'e of2-4 atmospheres, the 1 stirrers are set in operation, and'the reductionis stopped when the fall in pressure, in-

dicated by the gage, shows that the calculated quantity of hydrogen forperforming the semi-reduction, has beenconsumed. The 1 semi-reduction ofthe doubly unsatlu'ated geranic acid, C,.,H,',,O to dihydrogeranic acidC H O (inactive citronellicacid) is I ellected in the manner alreadydescribed, With the slight modification that, inorder to 1 stirring,whereupon the. 7

- hydrolinalool,

prevent esterification, use is made of either the freshly distilled,undiluted acid, or else of the said diluted with a multiple volume/ ofaqueous alcohol, with palladium protohydroxid. ld(()l l) or platinumprotohydroxid, lt(()l-I) as catalyzer, which, however, in view of thefact that the acid acts.

on calcium carbonate, are precipitated, not on this latter substance,but on a chemically inert catalyzer carrier, for example barium sulfate.the precipitated Id(()H) or I t(()ll) being reduced with hydrogen beforeuse. I"d(()I'l) or l.t(()ll) precipitated on calcium carbonate can,however, also be used, after previous reduction to metal by hydrogen,provided the ,qeranic acid be employed in the form of an aqueoussolution of its alkali salt. The reaction products are isolated in knownlnanner. For the purpose of purification they are distilled in a partialvacuum. In this way there is obtained from citral (C II KX),dihydrocitral inactive citronellal ((l dl fi) boiling point at 10mm.=79.81; D ZZ= 0.8535. Geraniol (C II O) furnishes dilrvdrogcraniolinactive citronellol ((,,,l"l. boiling point at 10 mm.::)9; D'Z=0.8488;melting point of the dihydrogeraniol-pyroracemate-scmi-carbazonc 112-l13(Bouveault, 7mm. (ic'ntr. Blazft, 1904, II, 440, In. 1). 112). Linalool((H H O) furnishes dihydrolinalool ((I,,H,,,O) boiling point at15mm.:0-3-92l DZ=0.8579. Phcnylurcthane of the dim. p. 60. Geranic acidIl O furnishes dihydrogeranic acid l H O (inactive citronellic acid) b.p. 9 mm.=139131: D 2: =O.927f7.

11. Complete "reduction of the olcfim'c tar- 71mm alcohols andaZdekydcs.IVlu-.n the complete'reduction of the olefinic terpenealcohols and aldehydes is in question, the employment of previouslycalculated quantities of hydrogen is superfluous, because the processceases when the carbon double linl ages in the molecules of the olefinicterpene derivatives have passed into the simple form. Under the workingconditions stated, no further reduction takes place. The work is carriedon in the way detailed in Exainple I. The complete reduction of thedoubly unsaturated geranic acid C H O and the simply unsaturatedcitronellic acid C H 0 to the completely saturated, inactive telra-'hydrogeranic acid C H O (inactive dihydrocitroncllic acid) or to theoptically active dihydrocitronellic acid, (Q,.,,H is also effected inthe manner given in Example I, with the difference that the hydrogen isallowed to act until saturation is complete. By filtering them off fromthe catalyzer, which can then be used over agaim'the reduction productsare obtained in quant ative amount. They are isolated in known &

manner, and purified by distillation in a partial vacuum. In this way,eitral, (1 11 0, and dihydrocitral (citronellal) (3 11 0, furnishtetrahydrocitral U II O, b. p. 16 mm.=8788; D}Z=O.83l. Geraniol, C l-lfi, and dihydro-geraniol (l,,,ll. furnish tetrahydro-geraniol, C I-I 0bfp. 18 mm. =1l2-1l3"; D=O.S329. Linalool, C H O, and dihydro-linalool,U II O, furnish tetrahydro-linalool, C H O: b. p. 153 mm.=-89;l)=0.8327; (001F078. (lefranic acid, (,,,I'l,,,() furnishestetrahvdrogeranic acid (J H O b. p. 10 mm.:1 l3- 134; D;=0.8$)9.Citronellic acid furnishes dihydrocitron'cllic acid. Q' H Q. (opticallyactive tetrahydro-geranic acid): b. p. 9 mm. =133; (a) ,19 +4.58;DZZ=O.S95.

In comparison with the previously known processes mentioned above, andwith that of German Patent 230724, the process exhibits the followingtechnical advantages: (1.) Only very small quantities of the expensivepalladium or platinum, acting as the hydrogen carrier are required; Thereduction product can be separated from the catalyzer in the simplestmanner, by filtration, not even a trace of the catalyzer is lost, andthe latter is fit for use over againwithout further treatment: (3.) Inthe case of doubly unsaturated compounds the reduction may be partial(scmi-) or complete, as desired; (4.) The process goes on quantatativelyat the ordinary temperature, without the formation of by-products; Thereduction occurs in a perfectly neutral solution so that thetranspositions and condensations to which the olefinic terpenederivativcs are liable under the influence of alkalies or acids cannottake Place.

I claim 1. The process for preparingsaturated aliphatic terpenederivatives containing oxygen-hydrogen groups which consists in mixingolefinic terpene derivatives containing oxygen-hydrogen groups withadhesion compounds of the platinum metal group free of acid andintroducinghydrogen at ordinary temperature in a, neutral medium intothesaid mixture.

2. The process for preparinn' saturated aliphatic terpene derivativescontainlng oxygen-hydrogen groups which consistsln mixing olefinicterpcne derivat ves conta ning oxygen-hydrogen groups with adhesioncompounds of the platinum metal group free of acid and introducinghydrogen at ordinary temperature under higher than atmospheric pressurein a neutral meduun into t1. said mixture.

Z-L'The process for preparing saturated aliphatic terpene derivativescontaining ox gen-hydrogen groups which consists 1n dissolving olefinicterpene derivatives con taining oxygen-hydrogen groups in organicaliphatic terpene derivatives containing oxygen-hydrogen groups whichconsists in mixing olefinic terpene derivatives containingoxygen-hydrogen groups with substances of the platinum metal group freeof acid previously deposited on ditferent pulverulent substances andintroducing hydrogen at ordinary temperature intothe said mixture.

The process for preparing half saturated aliphatic ter 'iene-derivativescontaining oxygen-hydrogen groups which consists in mixing olefinicterpene derivatives containing oxygen-hydrogen groups and twodoublelinkages of carbon with adhesion compounds of the platinum metal groupfree of acid and introducing hydrogen only in sufficient amount forhydrogenizing one double linkage of carbon at ordinary temperature in aneutral mediuminto the said mixture? 6. The process for preparing halfsaturated aliphatic terpene derivatives containing oxygen'hydrogengroups which consists in mixing olefinic terpene derivatives containingoxygen-hydrogen groups and two double linkages of carbon with adhesioncompoundsof the platinum metal group.

free of acid and introducing hydrogen only in sufiicient amount forhydrogenizing one double linkage of carbon at ordinary temperature underhigher than atmospheric pressure in a neutral medium into the saidmixture.

7. The process for preparing half saturated aliphaticterpene derivativescontaining oxygen-hydrogen groups which consists in dissolving olefinicterpene derivatives containing oxygen-hydrogen groups and two doublelinkages of carbon in organic solvents, mixing the said solution withadhesion compounds of the platinum metal group free of acid andintroducing hydrogen only in sufficient amount for hydrogenizing onedouble linkage of carbon at ordinary telnperature under higher thanatmospheric pressure in a neutral medium into the said mixture.

8. The process for preparing half saturated aliphatic terpenederivatives containing oxygen-hydrogen groups which consists indissolving olefinic terpene derivatives containing oxygen-hydrogengroupsand two double linkages of carbon in organic solvents, mixing thesaid solution with substances of the platinum metal group free of acidpreviously deposited on indifferent pulverulent substances andintroducing hydrogen only in sufficient amount for hydrogenizing onedouble linkage of carb'in at ordinary temperature under higher thanatmospheric pressure into the said mixture.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

CARL PAAL. Witnesses:

RUDOLPH FRICKER, ALICE DUNGER.

